1. Field of the Invention
The present invention relates to an apparatus for optical communication including an optical semiconductor module.
2. Description of Related Art
When communication through an optical fiber is used for cable television, mobile communication and the like, a light transmission circuit for transmitting analog or digital signals through an optical fiber is required to operate at a high speed in a wide range.
An apparatus including an optical semiconductor module connected to an optical fiber is used for optical communication. Among optical semiconductor modules, a DFB laser module of butterfly type has input/output lines of electrical signals at two sides thereof. Then, its contour is suitable to be packaged on a high frequency circuit board. FIG. 1 shows an example of a prior art package for an optical semiconductor module of the butterfly type 101. A high frequency circuit board 104, fixed on a metallic base 105, has a hole for receiving the optical semiconductor module 101 of butterfly type therein. The optical semiconductor module 101 is connected to an optical fiber 102, while input/output lines 106 thereof are provided at two sides and are connected electrically to a high frequency circuit on the circuit board 104.
When a system is constructed, a key in system design is to provide a simple light transmission circuit at a low cost. A Fabry-Perot laser diode which can be produced at a lower cost is beginning to be used for transmitting light signals instead of an expensive DFB laser. A Fabry-Perot laser diode module has a coaxial contour, and the input/output line of electrical signals of such a module extends along a longitudinal direction thereof. However, it is not necessarily suitable to be mounted to a high frequency circuit board.